Google launched its own ambitious wireless network primarily in the U.S. on Wednesday in partnership with Sprint and T-Mobile.

Calling it Project Fi, Google promised seamless wireless connections, initially for Nexus 6 smartphone users, whether they are within more than 1 million free and open Wi-Fi hotspots or within an LTE cellular network operated by Sprint or T-Mobile.

In a blog, Google
asked customers to sign up online to join an Early Access Program for the service. The service will initially be available on the Nexus 6 smartphone that Google builds with Motorola. Potential customers must request an invitation from Google on a separate site to get started.

Pricing was announced at $20 a month for talk, text, Wi-Fi tethering and international coverage in 120 counties, plus a flat $10 per gigabyte for cellular data while in the U.S. and abroad. One unusual feature is that Google will give users credit for unused data in any given month. Additional details were posted online.

In the blog, Nick Fox, vice president of Google communications products, said Google has developed new technology that gives users "better coverage by intelligently connecting you to the fastest available network at your location, whether it's Wi-Fi or one of our two partner LTE networks." Data will be secure through encryption once a connection is made, he said.

In addition to allowing users to freely move from Wi-Fi to cellular, Google said a user's phone number will live in the cloud so users can talk or text with that number on "just about any phone, tablet or laptop."

Fox said there are advantages to Google's involvement in the network as well as with the device and its software. "By designing across hardware, software and connectivity, we can more fully explore new ways for people to connect and communicate."

T-Mobile CEO John Legere blogged that Project Fi “is going to make people think differently about wireless -- and I love that.”

Sprint issued a statement saying it was "proud to enable Google's entry into the wireless industry as a service provider," adding that Sprint has empowered more than 100 successful MVNO's (Mobile Virtual Network Operator) in the U.S.

Many analysts have questioned how Google will make it as an MVNO, since some large projects have failed in the past decade. However, others believe Google will have greater control over the entire mobile experience for customers, which will only improve the company's ability to sell search and advertising services.

In January, when Google's interest in a wireless service first surfaced, MachNation analyst Dima Tokar argued that Google won't be a traditional MVNO and will use its network to start offering Google-branded Internet of Things services for homes and cars "to link all aspects of consumers' lives."